A long-running mystery in the United States involving illness in dogs fed chicken jerky treats is receiving fresh attention in the wake of reports that canines in Canada are getting sick, as well.

Kristin McEvoy, a spokeswoman for the Canadian Veterinary Medical Association, said last week that the association in the past month received about a dozen reports of dogs that had eaten various brands of chicken jerky developing a kidney disorder mimicking the genetic disease Fanconi syndrome.

The cases occurred across the country: British Columbia, Alberta, Saskatchewan and Ontario, McEvoy said, and involved dogs small and large, from shih tzus to retrievers.

The development of Fanconi-like syndrome in dogs associated with consumption of chicken jerky is new in Canada but has been ongoing in the United States since fall 2007.

That’s when veterinarians reported seeing an unusual number of dogs with a history of vomiting, lethargy and anorexia. Laboratory tests revealed hypokalemia, or low potassium; mild increase in liver enzymes; acidosis; glucosuria, or glucose in urine; and granular casts in urine.

The constellation of signs suggested a condition akin to Fanconi syndrome, an inherited condition in which the kidneys fail to resorb electrolytes and nutrients. Glucose “spills” into the urine, while blood-glucose levels are normal or low.

Between September 2007 and January 2009, the U.S. Food and Drug Administration (FDA) received more than 150 complaints about chicken jerky. The products were sold under a variety of brands and variously referred to as treats, strips and tenders but had one thing in common: They were made in China. An FDA investigation failed to identify any contaminants. However, the agency issued cautionary statements about chicken jerky in 2007 and 2008.

Cases of Fanconi-like syndrome appeared in Australia also, leading one maker of chicken treats there, KraMar Pet Company Pty Ltd., to recall its products in late 2008. The affected products were sold only in Australia and New Zealand.

Five months later, researchers in Australia discovered an association between Fanconi-like syndrome in dogs and consumption of dental chews called VeggieDents made by Virbac Animal Health. Confoundingly, VeggieDents contain no chicken products and were made in Vietnam. Although it had no evidence that VeggieDents were to blame for the illness, Virbac took the chews off the market in Australia. It continued to sell them in Europe, the United States and Asia, where no problems linked to VeggieDents had surfaced. Several months following the recalls, the Australian outbreak of Fanconi-like syndrome abated.

In the United States, meanwhile, reports have continued intermittently. Laura Alvey, a spokeswoman in the FDA’s Center for Veterinary Medicine, said that in the past year, the agency received 67 reports — 10 in June alone.

Alvey attributed the recent surge in complaints to a news alert from the American Veterinary Medical Association (AVMA) about the Canadian cases. “The numbers of Fanconi-like syndrome reports tend to increase after any type of press release,” she commented by e-mail. “... overall complaints continue.”

On a message board of the Veterinary Information Network (VIN), an online community for the profession, several practitioners in the United States said they had seen recent cases.

One is Dr. Jeanna Godfrey of Rockport, Texas. Her patient, a 10-year-old, 30-pound mixed-breed dog named Sweetie, presented on June 16 with a poor appetite, lethargy and what Godfrey called ADR typical of older patients — ADR for “ain’t doing right.”

Sweetie’s vital signs were normal, her diet was excellent, and she was up-to-date on vaccinations, heartworm prevention and flea control, Godfrey told the VIN News Service in an interview by e-mail. “The only obvious physical exam abnormality was a somewhat distended abdomen,” she said.

“Because of her age and no obvious clinical reason for her condition, we ran some blood work and a urinalysis,” Godfrey said. The results: All Sweetie’s liver enzymes were about twice the normal level. Urinalysis showed a trace of glucose, some blood and white blood cells.

“At first, I attributed the trace of glucose to ‘lab error’ since her blood glucose was in the normal range,” Godfrey recalled. “I asked the owner to think about any plants, pesticides, etc., Sweetie might have been exposed to, but she couldn’t pinpoint any type of toxin.”

During her lunch break, Godfrey happened to check e-mail and saw the AVMA alert about the Canadian cases. She called Sweetie’s owner and asked about treats.

“Sure enough, she had been giving Sweetie chicken jerky treats approximately three times a day for about five months,” Godfrey said. “I asked her to bring them in, and although the bag said ‘manufactured in the U.S.,’ in small print, it revealed ‘made in China.’ ”

Two weeks after her owner stopped feeding Sweetie the treats — and with no more treatment than a nutritional supplement and therapeutic diet designed to strengthen liver function, plus antibiotics for a urinary-tract infection — the dog’s urinalysis was normal and her blood work was nearly normal. Godfrey said Sweetie’s alkaline phosphatase — an indicator of liver damage or disease — was still above normal, but down from the previous results.

“Can I say for sure it was the chicken jerky treats? Probably not from a scientific standpoint,” Godfrey said. “Am I advising clients to read labels and not feed treats (sourced) in China regardless of where manufactured? You bet!”

The FDA’s Alvey said the agency’s investigation into the matter continues, but the cause of illness remains elusive.

Owing to the unresolved mystery, many veterinarians are, like Godfrey, cautioning clients to avoid all jerky treats, and/or products made in China or elsewhere in Asia.

On the home page of his website, Dr. Eric Orr, a practitioner in Orange City, Fla., warns in large red type: “Some jerky-treat products can cause kidney failure!” He goes on to advise, “Use caution when choosing foods and treats for your pets. ... For a safe treat for your dog: We often recommend fruits and vegetables. Carrots, green beans, bananas and apples, cooked or raw, are fine to feed dogs.”

All in moderation, of course, and with some caveats. In an interview, Orr noted that not all produce is safe. Grapes and raisins, for example, may be toxic to dogs. And even safe treats can be overdone. Orr’s seen that happen.

After he advised a client whose dog had a weight problem to give the pet low-calorie snacks such as single Cheerios, green beans and carrots, the dog came in sick a couple of weeks later.

In front of the veterinarian, the dog threw up what appeared to be a pound of carrots.